聚丙烯纤维对轻骨料混凝土基本力学性能影响试验研究

常用的页岩陶粒内部有多孔结构,易导致其机械强度较天然石子低,在轻骨料混凝土受力时更容易破坏,使轻骨料混凝土的基本力学性能降低。为增强轻骨料混凝土的基本力学性能,通过试验研究轻骨料混凝土的基本力学性能受聚丙烯纤维的掺量及其长度的影响规律。试验结果显示：聚丙烯纤维可有效改善轻骨料混凝土的抗压、抗拉性能。长度3 mm聚丙烯纤维,当掺量为0.3%～1.2%时,轻骨料混凝土的立方体抗压强度和劈裂抗拉性能分别上升4.4%～12.8%和4.5%～15.5%;对于纤维长度为6 mm、掺量为0.3%～0.9%时,立方体抗压强度和劈裂抗拉性能提升幅度则分别为11.5%～18.3%、14.3%～23.4%。6 mm聚丙烯纤维较3 mm能更有效提升轻骨料混凝土的抗压和抗拉性能,相对增幅分别达1.6%～10.4%和9.5%～10.6%。聚丙烯纤维的掺入整体上有利于轻骨料混凝土弹性模量的提升,但是效果和规律均不明显。     

改性聚丙烯纤维长度、掺量对混凝土性能影响的试验研究

介绍了亲水性聚丙烯纤维的掺量及长度对普通混凝土力学特性的影响情况、通过试验表明，掺入聚丙烯纤维可使普通混凝土的抗压强度、劈裂抗拉强度、抗收缩、抗冻融等性能有所改善．     

聚丙烯纤维混凝土的力学性能研究

通过七家实验室的试验数据,对聚丙烯纤维增强混凝土的力学性能进行数据分析,建立以普通混凝土的立方体抗压强度为基础的力学公式,并提出了ＰＦＲＣ的强度标准和设计值,以使这种混凝土能与现行国家混凝土规范并轨。     

含盐陶粒掺量对水泥混凝土力学性能的影响

为了探究含盐陶粒对骨料碎石的替代给混凝土力学性能带来的影响,给含盐陶粒混凝土的设计施工提供理论依据,试验通过对不同替代率各组试件的抗压试验、抗折试验及耐磨性试验研究分析,得出如下结论:1)含盐陶粒混凝土的抗压强度随陶粒对骨料碎石的替代率增大而减小,当替代率为100%时,强度下降幅度达39.3%;2)根据含盐陶粒混凝土界面破坏形态和机理,证实陶粒与水泥石的界面黏结力比普通集料和水泥石的界面黏结力大,陶粒本身强度决定了混凝土的强度;3)当含盐陶粒的替代率小于等于70%时,混凝土的抗折强度大于4 MPa,可以满足各交通量等级条件下的规范设计抗弯拉强度要求;4)含盐陶粒混凝土的磨耗值随着含盐陶粒的替代率增大而增大,当陶粒对骨料碎石的替代率达到100%时,混凝土的磨耗值增长幅度为67%,各组试件的磨耗值均小于规范3.6 kg/m~2的要求,证实了含盐陶粒混凝土能满足路面的耐磨性要求。     

聚丙烯纤维与聚酯纤维对混凝土力学性能影响的研究

为了研究水胶比、粉煤灰、聚丙烯纤维与聚酯纤维对混凝土力学性能的影响,通过正交试验,以混凝土抗压强度与劈裂抗拉强度为考核指标,确定出最优组合.根据最优组合制备的聚丙烯纤维和聚酯纤维混凝土与未掺纤维的混凝土相比较得出,聚丙烯纤维和聚酯纤维均使混凝土抗压强度略有提高,劈裂抗拉强度和抗折强度提高程度较大;聚丙烯纤维混凝土与聚酯纤维混凝土相比,前者抗压强度略高于后者,但后者劈裂抗拉强度和抗折强度高于前者.     

高掺量合成纤维混凝土力学性能研究

为研究高掺量下合成纤维混凝土的力学性能,在0～3%纤维体积率(Vf)范围内,对4种合成纤维混凝土进行了试验研究,并与钢纤维混凝土进行对比。结果表明:随着Vf增大,混凝土抗压强度、弹性模量降低,但降幅不大,使用粗纤维对保证混凝土抗压强度和弹性模量更有利。劈拉强度、抗弯强度和抗弯韧性随Vf增大而增大,细纤维在应用时掺量不宜过高,否则会引起增强效率降低。束状纤维和粗纤维在高掺量下分散性和增强效果良好,Vf在3%以上仍具有进一步提高混凝土力学性能的可能。高强度高弹性模量合成纤维对混凝土劈拉、抗弯强度具有与钢纤维同等的增强效应。     

聚丙烯纤维水泥稳定碎石力学性能试验研究

为了研究聚丙烯纤维对水泥稳定碎石力学性能的影响,对聚丙烯纤维水泥稳定碎石和普通水泥稳定碎石的抗压强度、劈裂抗拉强度、抗压回弹模量、抗弯拉强度和抗弯拉弹性模量进行了测试,给出了聚丙烯纤维体积掺量合适的建议范围为0.06%~0.08%.同时根据试验结果的回归分析,得出了聚丙烯纤维体积掺量与聚丙烯纤维水泥稳定碎石各力学性能指标的关系式.试验结果表明:聚丙烯纤维的掺入对水泥稳定碎石的各种强度均有一定的提高,能有效地减小抗压回弹模量和抗弯拉弹性模量,提高了其抗变形能力;在聚丙烯纤维体积掺量小于0.1%的范围内,随着纤维掺量的增加,水泥稳定碎石各种强度有增加的趋势,而其抗压回弹模量和抗弯拉弹性模量是逐渐降低的.     

粉煤灰掺量对水工混凝土力学性能的影响

通过粉煤灰混凝土基本力学性能试验,分析了粉煤灰掺量、水灰比、龄期等因素对水工混凝土抗压强度、劈拉强度和抗压弹模的影响,探讨了粉煤灰对混凝土力学性能的影响机理.试验结果表明,随着粉煤灰掺量的增加,混凝土的早期强度有所降低,后期强度有明显提高.     

聚丙烯纤维混凝土的工作性与力学性能

研究了聚丙烯纤维和粉煤灰对混凝土的工作性和力学性能的影响.试验结果表明:在混凝土中掺加1.0‰聚丙烯纤维,可以降低新拌混凝土坍落度经时损失,使混凝土拌合物的泌水率降低了35%.与普通混凝土相比,聚丙烯纤维对混凝土的抗压强度影响不大,但28 d劈拉强度提高45%,抗折强度提高19%,拉压比提高46%.同时掺加聚丙烯纤维和粉煤灰,混凝土坍落度经时损失与单掺聚丙烯纤维混凝土相似,但可以改善混凝土泌水率、劈拉强度和抗折强度.     

高温作用对大掺量粉煤灰混凝土力学性能影响

研究了高温作用对大掺量粉煤灰混凝土(HFCC)立方体力学性能的影响,探讨了不同加热温度、不同粉煤灰掺量与HFCC残余强度的关系.将粉煤灰掺量30%、40%和50%的混凝土立方体试块加热至250,450,550和650℃进行强度测试,并与素混凝土(不掺粉煤灰)试块进行对比.研究结果表明,随着温度升高,HFCC残余抗压、劈裂抗拉强度均出现明显退化,劈裂抗拉强度退化尤为明显;随着粉煤灰的掺入,粉煤灰掺量对强度退化率的影响具有复杂性:高温后HFCC抗压强度退化率均低于普通混凝土强度退化率;劈裂抗拉强度退化率除粉煤灰掺量30%外均低于普通混凝土退化率.在试验基础上建立HFCC高温后立方体残余抗压强度、残余劈裂抗拉强度与温度、粉煤灰掺量的定量关系,为高温后HFCC材料强度评估及修复提供依据.     

The Mechanical Properties of Polypropylene Fiber Reinforced Concrete

The compressive, shear strengths and abrasion-erosion resistance as well as flexural properties of two polypropyenc fiber reinforced concretes and the comparison with a steel fiber reinforced concrete were reported. The exprimental results show that a low content of polypropylene fiber (0.91 kg/m^3 of concrete ) slightly decreases the compressive and shear strengths, and appreciably increased the flexural strength, but obviously enhances the toughness index and fracture energy for the concrete with the same mix proportion, coasequently it plays a role of anti-cracking and improving toughness in concrete. Moreover, the polypropylene mesh fiber is better than the polypropylene monofilament fiber in improving flexaral strength and toughness of concrete, but the types of polypropylene fibers are inferior to steel fiber. All the polypropylene and steel fibers have no great beneficial effect on the abrasion-erosion resistance of concrete.     

改性聚丙烯纤维混疑土的力学性能

为克服水泥混凝土脆性大、易开裂的缺点，在混凝土的拌制过程中加入了改性处理的聚丙烯纤维，并通过空白和加纤维的混凝土多种力学性能研究的对比试验，发现在1m^3水泥混凝土中掺入长度为19mm的0．9kg改性聚丙烯纤维，对其诸多的力学性能均有明显的增强作用．     

Impact on concrete mechanical properties of polypropylene fiber

在混凝土中加入不同掺量的聚丙烯纤维,形成聚丙烯纤维混凝土,通过立方体抗压强度试验、弯曲韧性试验、早期收缩抗裂试验,并与素混凝土试验结果进行对比,来确定不同掺量的聚丙烯纤维对于混凝土各个力学性能的影响,从而确定最佳的聚丙烯纤维掺量。     

Flexural Strength and Behavior of Polypropylene Fiber Reinforced Concrete Beams

The strength and deformation characteristics of polypropylene fiber reinforced concrete ( PFRC) beams were investigated by four-point bending procedures in this paper. Two kinds of polypropylene fibers with different fiber contents (0.2% , 0.5% , 1.0% and 1.5% ) by volume were used in, the beam, which measured 100 × 100 mm with a span of 300 mm. It was found that the strength of the reinforced concrete beams was significantly decreased, whereas the flexural toughness was improved, compared to those unreinforced concrete beams. Geometry properties and volume contents of polypropylene fiber were considered to be important factors for improving the flexural toughness. Moreover, the composite mechanism between polypropylene fiber and concrete was analyzed and discussed.     

改性聚丙烯纤维混凝土抗渗性能的试验研究

通过对两种不同纤维掺量的混凝土试件和普通无纤维混凝土试件进行抗渗试验的对比，研究了在混凝土中掺入不同掺量的改性聚丙烯纤维对混凝土抗渗性能的改善效果和影响规律，探讨了水泥基纤维混凝土的抗渗机理及性能特点。     

Preparation and mechanical properties of polypropylene fiber reinforced calcined kaolin-fly ash based geopolymer

To improve the environmental benefits and solve the problems of large shrinkage and high brittleness, the partial replacement of calcined kaolin by fly ash as a raw material for geopolymer synthesis and the influences of polypropylene (PP) fiber on the mechanical properties and volume stability were investigated. The results show that compressive strength of the geopolymer containing 33.3%(mass fraction) fly ash by steam curing at 80 °C for 6 d is improved by 35.5%. The 3-day compressive strength, flexural strength and impacting energy of geopolymers containing 0.05%PP fiber increase by 67.8%, 36.1% and 6.25%, while the shrinkage and modulus of compressibility decrease by 38.6% and 31.3%, respectively. The results of scanning electron microscopy (SEM) and the appearances of crack growths confirm that PP fiber can offer a bridging effect over the harmful pores and defects and change the expanding ways of cracks, resulting in a great improvement of strength and toughness. Foundation item: Project(2006AA06Z225) supported by the National High-Tech Research and Development Program of China     

剑麻纤维增强珊瑚混凝土力学性能试验研究

为研究不同剑麻纤维掺量下珊瑚混凝土力学性能的变化规律,通过对剑麻纤维增强珊瑚混凝土的立方体抗压强度、劈裂抗拉强度、抗折强度及其微观结构进行试验研究,确定剑麻纤维的最佳添加量,为进一步研究剑麻纤维增强珊瑚混凝土其它性能及应用提供参考.试验结果表明,剑麻纤维的掺入对珊瑚混凝土立方体抗压强度的影响很小,掺量3~4.5 kg/m3的剑麻纤维可以显著提高珊瑚混凝土的抗折强度及劈裂抗拉强度,剑麻纤维的掺入可以改善珊瑚混凝土的脆性,使其破坏时表现出良好的延性.     

纺织废料再生纤维增强混凝土力学性能的研究

对纺织废地毯再生纤维增强混凝土的力学性能进行实验研究．结果表明，含量为2％的纺织废地毯再生纤维增强混凝土的抗压强力、抗剪切强力和抗弯曲强力等力学性能较普通混凝土有所提高；干燥收缩性以及由此引起的韧性及能量吸收性较普通混凝土均有较大改善．这种混凝土若能得到广泛使用，还可节约资源、保护环境．     

Mechanical properties of layered steel fiber and hybrid fiber reinforced concrete

To explore a new structure form of fiber reinforced concrete, namely, the layered steel fiber and layered hybrid fiber reinforced concrete （LSFRC and LHFRC）, the mechanical properties of LSFRC and LHFRC, such as compressive strength, tensile strength, flexural strength, fatigue and durability were focused on. The experimental results show that LSFRC and LHFRC can improve the flexural strength of concrete by 20%-50%. In the aspect of improving the flexural strength of concrete, adulterant rate has more obvious effect than length/diameter ratio. Double logarithmic fatigue equation considered liveability was founded. The impermeability of LHFRC is superior to LSFRC and plain concrete （C）. However, the porosity of LHFRC is lower than LSFRC and C. The shrinkage of LHFRC at every age is obviously lower than C. The antifreeze durability of LHFRC is also better than C.